What is the ohm value of this resistor?

[zamistro]

This is the ignition resistor off my '67 IH 2424 4 cylinder gas. Any idea what the ohm value is? I know what my ohm meter says, but who knows if that affected by the condition of the resistor.

Patent is the only visible marking.

 

[Non-farmer]

Those things can vary wildly in resistance. Supposedly the ones in 12 volt conversion kits (for my tractor, anyway) are 1.5 ohms, but the one I got was 3.5 ohms, and I read someone here got one that was 5.5 ohms. The meter measurement is the only way to tell. Measure your leads just touched to each other and then subtract that number from what the meter tells you for the resistor. Set the meter to the lowest possible range, as long as that's not less than the resistor and leads combined.

 

[wore out]

This is the ignition resistor off my '67 IH 2424 4 cylinder gas. Any idea what the ohm value is? I know what my ohm meter says, but who knows if that affected by the condition of the resistor. View attachment 122010Patent is the only visible marking.

That does not appear to be OEM, IIRC, the original would have had screw terminals, so anything anyone can tell you is just a guess,

You can find identical-looking resistors in the range of 0.6 Ohms to 2 Ohms, and probably others. Some similar-looking ignition resistors are "PTC" (Positive Temperature Coefficient) meaning that their resistance increases as they heat up. That type is typically used in systems without a "starting bypass".

The bottom line is that the resistor plus the coil primary resistance will add up to 3 Ohms or more.

Another way to check if the resistance is reasonable is to check primary ignition CURRENT.

Fully-charged battery, points "closed", primary current should be in the 3.5 to 4 Amps range. Much less and spark may be on the weak side, if measured current is much over 4 Amps this is approaching the point of the coil overheating and shortened breaker point life.

What resistance measurement are you getting? Have you checked the coil's primary resistance? Do you have your Ohmmeter set on the lowest range? Before measurement, did you short the test leads together and note if it read "0", if NOT, make note of the reading and subtract it from the measured reading of the resistor or coil.

 

[John T]

Good info from wore out. One way to look at it is if you have a 12 volt tractor but a 6 volt coil plus an external ballast (may or may NOT be your case), the ballast would be the same resistance of the coil to form a 50 50 voltage divider thus dropping 6 volts across the ballast and 6 across the coil. Some cheaper VOMs are NOT real accurate in the low ohms range so get your volt meter and measuer the voltage drops across the coil and ballast and see what ohms it shows ??? My best pure and worthless guess is the resistor is in the 1.5 ohms range.

John T

 

[Duner Wi]

Lookup values for Std Motor Products RU11 as used on Chrysler products starting in the 50s up into the early 70s.

 

[wore out]

Lookup values for Std Motor Products RU11 as used on Chrysler products starting in the 50s up into the early 70s.

What will that prove, considering there are many, many primary resistors that are visually identical, but with greatly different resistance characteristics?

 

[Duner Wi]

Wore out ,the question is "what is the ohm value of this resistor" answer. About 1.65 ohms. OEM to tractor I think was ACDelco F1104 with OHM value about Where did I go wrong.? I am doing a bit of guessing.

 

[wore out]

Wore out ,the question is "what is the ohm value of this resistor" answer. About 1.65 ohms. OEM to tractor I think was ACDelco F1104 with OHM value about Where did I go wrong.? I am doing a bit of guessing.

We have no reason to believe that his resistor is OEM (it doesn't look like it to me), ans there's no identifying marks on it, so how can we answer the O.P.'s question with any degree of certainty?

The way I read the question, he asked what the value of the resistor in the photo is, NOT what originally was there, or what "should" be there.

As to what "should" be there, we also do not know if the coil is OEM (or equivalent) or what it may actually be.

Wonder what the measured resistance value the O.P. determined, he's being pretty close-lipped about that.

On the other hand, I agree with you, and would EXPECT the value of his resistor to be in the 1.5 to 2 Ohms range.

But guesses and assumptions don't always work out!

 

[Geo-TH,In]

Good info from wore out. One way to look at it is if you have a 12 volt tractor but a 6 volt coil plus an external ballast (may or may NOT be your case), the ballast would be the same resistance of the coil to form a 50 50 voltage divider thus dropping 6 volts across the ballast and 6 across the coil. Some cheaper VOMs are NOT real accurate in the low ohms range so get your volt meter and measuer the voltage drops across the coil and ballast and see what ohms it shows ??? My best pure and worthless guess is the resistor is in the 1.5 ohms range.

John T

John t
Totally agree. Put the ballast in series with the coil and connect to 12 volts.
I looked long and hard to buy one that gave me a 50/50. 6 v across the coil and 6 v across the ballast. I ended up using my spare ballast I carry in my 1978 Dodge Aspen wagon. All the ballasts I bought online got sent back.

How are you doing? Are you on the road again? Instead of driving a long distance, I plan to drive to the airport and fly. No way do I want to get stranded in the middle of nowhere and have my son drive me 500 miles to Indiana.

 

[Duner Wi]

Check out patent #D254186. I estimate traffic on this site would be down 75% if we stuck to "just the facts". Most all try to be helpful but some replies go off the rails and wander off from the question asked. In the end most every one is genuinely trying to be helpful.

 

[wore out]

Check out patent #D254186. I estimate traffic on this site would be down 75% if we stuck to "just the facts". Most all try to be helpful but some replies go off the rails and wander off from the question asked. In the end most every one is genuinely trying to be helpful.

If we "stuck to the facts" the answer to the O.P.'s question would have been "it is impossible to answer with the information provided".

Can you disagree with that?